The ion implanting apparatus is used to change the optoelectronic property of the wafer by adding specific dopants therein. The ion implanting apparatus ionizes the dopant to be added into the wafer to form an ionic beam at first. The ion beam is then accelerated up to a predetermined kinetic energy by an electromagnetic lens, and then bombards onto the surface of the wafer. Since the ion beam possesses the predetermined kinetic energy, it will penetrate into the wafer to a certain depth after bombarding the surface of the wafer. Some ions suffer energy losses during the penetration process due to the successive collision with atoms of the wafer continuously. Eventually, the ions stop and are embedded in the clearance of crystal lattices of the wafer, and the dopant is thus called “implanted”. In addition, the successive collision between the ions with high energy and the atom arranged in crystal structure of the wafer results in that the original crystal structure with a regular order is disordered due to the different exposure dosage of the ion beam. As a result, the electrical property of certain regions is changed at varying degrees.
The conventional implanting base of the ion implanting apparatus can be mainly divided into two designs. The first design uses a rotating circular base, on which many wafers are positioned. Each wafer receives a uniform ion dosage through the cooperation of the whirling motion of the circular base with the wagging motion of the axle (EP 1035560, EP 1037255, U.S. 2002/079465 and U.S. Pat. No. 6,429,442). The second design uses a fixed implanting base, wherein only a single wafer is implanted in each batch (U.S. 2003/070316 and EP 0385707).
The ion beam and the implanting mechanism can also be divided into two designs. The first design uses an ion beam with a fixed direction, wherein the ion beam irradiates on the surface of the wafer directly, and the implanting base possesses a rotatable mechanism and a wagging mechanism of the axle. For the ion implanting apparatus possesses such a design, the magnetic mirror system for the ion beam is quite simple, but the mechanical design for the implanting base requires a high precision (SEE EP 1035560, EP 1037255, U.S. 2002/079465 and U.S. Pat. No. 6,429,442). The second design uses a scanning ion beam and a fixed implanting base, namely the implanting base does not possess any mechanism for rotating or translational motion (SEE U.S. 2003/070316 and EP 0385707). For the ion implanting apparatus with such a design, the direction of the scanning ion beam is not perpendicular to the surface of the wafer.